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FI Syndrome

Genetic Research

FOAL IMMUNO DEFICIENCY SYNDROME: Its relevance to survival of Extensively Grazing Breed Lines

FOAL IMMUNODEFICIENCY SYNDROME (FIS) is a syndrome that was first discovered in the Fell pony breed but has since been reported in the Dales pony (and might also affect other breeds).

FIS is a fatal immunodeficiency disease affecting foals within the first three months of life.

A DNA test for the recessive gene causing the disease has been developed by researchers at Liverpool University’s School of Veterinary Science and Newmarket Animal Health Trust.

Foals must receive the defective gene form both the sire and the dam in order to contract the disease. If a pony has received the defective gene from only one parent, the foal appears quite normal, retains all the characteristics of a true Fell pony and will never develop the disease. Such ponies are termed CARRIERS.

FIS is relevant to any discussion of stallions from extensively grazing herds because testing of stallions to determine whether they are carriers is not yet compulsory or even routine.

There is no method of assessing to what extent carrier stallions are not being used to breed. This might constitute a form of genetic erosion within the breed, because important genes may be lost over a prolonged time period.

The disease can be eventually eradicated if known carriers are always mated with non-carriers, simultaneously conserving all other genetic material that constitutes the breed .

The question arises, should testing of stallions be compulsory?

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